<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc) {
 //给定范围获得随机颜色
 Random random = new Random();
 if(fc>255) fc=255;
 if(bc>255) bc=255;
 int r=fc+random.nextInt(bc-fc);
 int g=fc+random.nextInt(bc-fc);
 int b=fc+random.nextInt(bc-fc);
 return new Color(r,g,b);
}
%>
<%
    //设置页面不缓存
    response.setHeader("Pragma","No-cache");
    response.setHeader("Cache-Control","no-cache");
    response.setDateHeader("Expires", 0);
    // 在内存中创建图象
    int width=60, height=20;
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    // 获取图形上下文
    Graphics g = image.getGraphics();
    //生成随机类
    Random random = new Random();
    // 设定背景色
    g.setColor(getRandColor(200,250));
    g.fillRect(0, 0, width, height);
    //设定字体
    g.setFont(new Font("Times New Roman",Font.PLAIN,18));
    //画边框
    //g.setColor(new Color());
    //g.drawRect(0,0,width-1,height-1);

    // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
    g.setColor(getRandColor(160,200));
    for (int i=0;i<155;i++) {
  int x = random.nextInt(width);
  int y = random.nextInt(height);
  int xl = random.nextInt(12);
  int yl = random.nextInt(12);
  g.drawLine(x,y,x+xl,y+yl);
    }
    // 取随机产生的认证码(4位数字)
    String sRand="";
    for (int i=0;i<4;i++) {
        String rand=String.valueOf(random.nextInt(10));
        sRand+=rand;
        // 将认证码显示到图象中
        g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
        g.drawString(rand,13*i+6,16);
    }
    // 将认证码存入SESSION
    session.setAttribute("KAPTCHA_SESSION_KEY",sRand);
    // 图象生效
    g.dispose();
    // 输出图象到页面
    ImageIO.write(image, "JPEG", response.getOutputStream());
 out.clear();
 out = pageContext.pushBody();
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title></title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
   
  </body>
</html>
